Priority level adaptation in a dispersed storage network

ABSTRACT

A processing system in a dispersed storage network is configured to access write sequence information corresponding to a write sequence; determine whether to elevate a priority level of the write sequence; when the processing system determines to elevate the priority level of the write sequence, elevate the priority level of the write sequence; determine whether to lower the priority level of the write sequence; and when the processing system determines to lower the priority level of the write sequence, the processing system lowers the priority level of the write sequence.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present U.S. Utility Patent Application claims priority pursuant to35 U.S.C. § 120 as a continuation-in-part of U.S. Utility applicationSer. No. 13/683,951, entitled “PRIORITIZATION OF MESSAGES OF A DISPERSEDSTORAGE NETWORK”, filed Nov. 21, 2012, which claims priority pursuant to35 U.S.C. § 119(e) to U.S. Provisional Application No. 61/564,185,entitled “OPTIMIZING PERFORMANCE OF DISPERSED STORAGE NETWORK”, filedNov. 28, 2011, both of which are hereby incorporated herein by referencein their entirety and made part of the present U.S. Utility PatentApplication for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION

Technical Field of the Invention

This invention relates generally to computer networks and moreparticularly to dispersing error encoded data.

Description of Related Art

Computing devices are known to communicate data, process data, and/orstore data. Such computing devices range from wireless smart phones,laptops, tablets, personal computers (PC), work stations, and video gamedevices, to data centers that support millions of web searches, stocktrades, or on-line purchases every day. In general, a computing deviceincludes a central processing unit (CPU), a memory system, userinput/output interfaces, peripheral device interfaces, and aninterconnecting bus structure.

As is further known, a computer may effectively extend its CPU by using“cloud computing” to perform one or more computing functions (e.g., aservice, an application, an algorithm, an arithmetic logic function,etc.) on behalf of the computer. Further, for large services,applications, and/or functions, cloud computing may be performed bymultiple cloud computing resources in a distributed manner to improvethe response time for completion of the service, application, and/orfunction. For example, Hadoop is an open source software framework thatsupports distributed applications enabling application execution bythousands of computers.

In addition to cloud computing, a computer may use “cloud storage” aspart of its memory system. As is known, cloud storage enables a user,via its computer, to store files, applications, etc. on an Internetstorage system. The Internet storage system may include a RAID(redundant array of independent disks) system and/or a dispersed storagesystem that uses an error correction scheme to encode data for storage.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of an embodiment of a dispersed ordistributed storage network (DSN) in accordance with the presentinvention;

FIG. 2 is a schematic block diagram of an embodiment of a computing corein accordance with the present invention;

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data in accordance with the present invention;

FIG. 4 is a schematic block diagram of a generic example of an errorencoding function in accordance with the present invention;

FIG. 5 is a schematic block diagram of a specific example of an errorencoding function in accordance with the present invention;

FIG. 6 is a schematic block diagram of an example of a slice name of anencoded data slice (EDS) in accordance with the present invention;

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of data in accordance with the present invention;

FIG. 8 is a schematic block diagram of a generic example of an errordecoding function in accordance with the present invention;

FIG. 9A is a schematic block diagram of an embodiment of storage modulein accordance with the present invention;

FIG. 9B is a schematic block diagram of an embodiment of computingsystem in accordance with the present invention; and

FIG. 10 is a logic diagram of an example of a method of in accordancewith the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram of an embodiment of a dispersed, ordistributed, storage network (DSN) 10 that includes a plurality ofcomputing devices 12-16, a managing unit 18, an integrity processingunit 20, and a DSN memory 22. The components of the DSN 10 are coupledto a network 24, which may include one or more wireless and/or wirelined communication systems; one or more non-public intranet systemsand/or public internet systems; and/or one or more local area networks(LAN) and/or wide area networks (WAN).

The DSN memory 22 includes a plurality of storage units 36 that may belocated at geographically different sites (e.g., one in Chicago, one inMilwaukee, etc.), at a common site, or a combination thereof. Forexample, if the DSN memory 22 includes eight storage units 36, eachstorage unit is located at a different site. As another example, if theDSN memory 22 includes eight storage units 36, all eight storage unitsare located at the same site. As yet another example, if the DSN memory22 includes eight storage units 36, a first pair of storage units are ata first common site, a second pair of storage units are at a secondcommon site, a third pair of storage units are at a third common site,and a fourth pair of storage units are at a fourth common site. Notethat a DSN memory 22 may include more or less than eight storage units36. Further note that each storage unit 36 includes a computing core (asshown in FIG. 2, or components thereof) and a plurality of memorydevices for storing dispersed error encoded data.

In various embodiments, each of the storage units operates as adistributed storage and task (DST) execution unit, and is operable tostore dispersed error encoded data and/or to execute, in a distributedmanner, one or more tasks on data. The tasks may be a simple function(e.g., a mathematical function, a logic function, an identify function,a find function, a search engine function, a replace function, etc.), acomplex function (e.g., compression, human and/or computer languagetranslation, text-to-voice conversion, voice-to-text conversion, etc.),multiple simple and/or complex functions, one or more algorithms, one ormore applications, etc. Hereafter, a storage unit may be interchangeablyreferred to as a DST execution unit and a set of storage units may beinterchangeably referred to as a set of DST execution units.

Each of the computing devices 12-16, the managing unit 18, and theintegrity processing unit 20 include a computing core 26, which includesnetwork interfaces 30-33. Computing devices 12-16 may each be a portablecomputing device and/or a fixed computing device. A portable computingdevice may be a social networking device, a gaming device, a cell phone,a smart phone, a digital assistant, a digital music player, a digitalvideo player, a laptop computer, a handheld computer, a tablet, a videogame controller, and/or any other portable device that includes acomputing core. A fixed computing device may be a computer (PC), acomputer server, a cable set-top box, a satellite receiver, a televisionset, a printer, a fax machine, home entertainment equipment, a videogame console, and/or any type of home or office computing equipment.Note that each of the managing unit 18 and the integrity processing unit20 may be separate computing devices, may be a common computing device,and/or may be integrated into one or more of the computing devices 12-16and/or into one or more of the storage units 36.

Each interface 30, 32, and 33 includes software and hardware to supportone or more communication links via the network 24 indirectly and/ordirectly. For example, interface 30 supports a communication link (e.g.,wired, wireless, direct, via a LAN, via the network 24, etc.) betweencomputing devices 14 and 16. As another example, interface 32 supportscommunication links (e.g., a wired connection, a wireless connection, aLAN connection, and/or any other type of connection to/from the network24) between computing devices 12 & 16 and the DSN memory 22. As yetanother example, interface 33 supports a communication link for each ofthe managing unit 18 and the integrity processing unit 20 to the network24.

Computing devices 12 and 16 include a dispersed storage (DS) clientmodule 34, which enables the computing device to dispersed storage errorencode and decode data as subsequently described with reference to oneor more of FIGS. 3-8. In this example embodiment, computing device 16functions as a dispersed storage processing agent for computing device14. In this role, computing device 16 dispersed storage error encodesand decodes data on behalf of computing device 14. With the use ofdispersed storage error encoding and decoding, the DSN 10 is tolerant ofa significant number of storage unit failures (the number of failures isbased on parameters of the dispersed storage error encoding function)without loss of data and without the need for a redundant or backupcopies of the data. Further, the DSN 10 stores data for an indefiniteperiod of time without data loss and in a secure manner (e.g., thesystem is very resistant to unauthorized attempts at accessing thedata).

In operation, the managing unit 18 performs DS management services. Forexample, the managing unit 18 establishes distributed data storageparameters (e.g., vault creation, distributed storage parameters,security parameters, billing information, user profile information,etc.) for computing devices 12-14 individually or as part of a group ofuser devices. As a specific example, the managing unit 18 coordinatescreation of a vault (e.g., a virtual memory block associated with aportion of an overall namespace of the DSN) within the DSN memory 22 fora user device, a group of devices, or for public access and establishesper vault dispersed storage (DS) error encoding parameters for a vault.The managing unit 18 facilitates storage of DS error encoding parametersfor each vault by updating registry information of the DSN 10, where theregistry information may be stored in the DSN memory 22, a computingdevice 12-16, the managing unit 18, and/or the integrity processing unit20.

The DSN managing unit 18 creates and stores user profile information(e.g., an access control list (ACL)) in local memory and/or withinmemory of the DSN memory 22. The user profile information includesauthentication information, permissions, and/or the security parameters.The security parameters may include encryption/decryption scheme, one ormore encryption keys, key generation scheme, and/or dataencoding/decoding scheme.

The DSN managing unit 18 creates billing information for a particularuser, a user group, a vault access, public vault access, etc. Forinstance, the DSN managing unit 18 tracks the number of times a useraccesses a non-public vault and/or public vaults, which can be used togenerate a per-access billing information. In another instance, the DSNmanaging unit 18 tracks the amount of data stored and/or retrieved by auser device and/or a user group, which can be used to generate aper-data-amount billing information.

As another example, the managing unit 18 performs network operations,network administration, and/or network maintenance. Network operationsincludes authenticating user data allocation requests (e.g., read and/orwrite requests), managing creation of vaults, establishingauthentication credentials for user devices, adding/deleting components(e.g., user devices, storage units, and/or computing devices with a DSclient module 34) to/from the DSN 10, and/or establishing authenticationcredentials for the storage units 36. Network administration includesmonitoring devices and/or units for failures, maintaining vaultinformation, determining device and/or unit activation status,determining device and/or unit loading, and/or determining any othersystem level operation that affects the performance level of the DSN 10.Network maintenance includes facilitating replacing, upgrading,repairing, and/or expanding a device and/or unit of the DSN 10.

The integrity processing unit 20 performs rebuilding of ‘bad’ or missingencoded data slices. At a high level, the integrity processing unit 20performs rebuilding by periodically attempting to retrieve/list encodeddata slices, and/or slice names of the encoded data slices, from the DSNmemory 22. For retrieved encoded slices, they are checked for errors dueto data corruption, outdated version, etc. If a slice includes an error,it is flagged as a ‘bad’ slice. For encoded data slices that were notreceived and/or not listed, they are flagged as missing slices. Badand/or missing slices are subsequently rebuilt using other retrievedencoded data slices that are deemed to be good slices to produce rebuiltslices. The rebuilt slices are stored in the DSN memory 22.

FIG. 2 is a schematic block diagram of an embodiment of a computing core26 that includes a processing module 50, a memory controller 52, mainmemory 54, a video graphics processing unit 55, an input/output (IO)controller 56, a peripheral component interconnect (PCI) interface 58,an IO interface module 60, at least one IO device interface module 62, aread only memory (ROM) basic input output system (BIOS) 64, and one ormore memory interface modules. The one or more memory interfacemodule(s) includes one or more of a universal serial bus (USB) interfacemodule 66, a host bus adapter (HBA) interface module 68, a networkinterface module 70, a flash interface module 72, a hard drive interfacemodule 74, and a DSN interface module 76.

The DSN interface module 76 functions to mimic a conventional operatingsystem (OS) file system interface (e.g., network file system (NFS),flash file system (FFS), disk file system (DFS), file transfer protocol(FTP), web-based distributed authoring and versioning (WebDAV), etc.)and/or a block memory interface (e.g., small computer system interface(SCSI), internet small computer system interface (iSCSI), etc.). The DSNinterface module 76 and/or the network interface module 70 may functionas one or more of the interface 30-33 of FIG. 1. Note that the IO deviceinterface module 62 and/or the memory interface modules 66-76 may becollectively or individually referred to as IO ports.

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data. When a computing device 12 or 16 has data tostore it disperse storage error encodes the data in accordance with adispersed storage error encoding process based on dispersed storageerror encoding parameters. Here, the computing device stores data object40, which can include a file (e.g., text, video, audio, etc.), or otherdata arrangement. The dispersed storage error encoding parametersinclude an encoding function (e.g., information dispersal algorithm,Reed-Solomon, Cauchy Reed-Solomon, systematic encoding, non-systematicencoding, on-line codes, etc.), a data segmenting protocol (e.g., datasegment size, fixed, variable, etc.), and per data segment encodingvalues. The per data segment encoding values include a total, or pillarwidth, number (T) of encoded data slices per encoding of a data segmenti.e., in a set of encoded data slices); a decode threshold number (D) ofencoded data slices of a set of encoded data slices that are needed torecover the data segment; a read threshold number (R) of encoded dataslices to indicate a number of encoded data slices per set to be readfrom storage for decoding of the data segment; and/or a write thresholdnumber (W) to indicate a number of encoded data slices per set that mustbe accurately stored before the encoded data segment is deemed to havebeen properly stored. The dispersed storage error encoding parametersmay further include slicing information (e.g., the number of encodeddata slices that will be created for each data segment) and/or slicesecurity information (e.g., per encoded data slice encryption,compression, integrity checksum, etc.).

In the present example, Cauchy Reed-Solomon has been selected as theencoding function (a generic example is shown in FIG. 4 and a specificexample is shown in FIG. 5); the data segmenting protocol is to dividethe data object into fixed sized data segments; and the per data segmentencoding values include: a pillar width of 5, a decode threshold of 3, aread threshold of 4, and a write threshold of 4. In accordance with thedata segmenting protocol, the computing device 12 or 16 divides dataobject 40 into a plurality of fixed sized data segments (e.g., 1 throughY of a fixed size in range of Kilo-bytes to Tera-bytes or more). Thenumber of data segments created is dependent of the size of the data andthe data segmenting protocol.

The computing device 12 or 16 then disperse storage error encodes a datasegment using the selected encoding function (e.g., Cauchy Reed-Solomon)to produce a set of encoded data slices. FIG. 4 illustrates a genericCauchy Reed-Solomon encoding function, which includes an encoding matrix(EM), a data matrix (DM), and a coded matrix (CM). The size of theencoding matrix (EM) is dependent on the pillar width number (T) and thedecode threshold number (D) of selected per data segment encodingvalues. To produce the data matrix (DM), the data segment is dividedinto a plurality of data blocks and the data blocks are arranged into Dnumber of rows with Z data blocks per row. Note that Z is a function ofthe number of data blocks created from the data segment and the decodethreshold number (D). The coded matrix is produced by matrix multiplyingthe data matrix by the encoding matrix.

FIG. 5 illustrates a specific example of Cauchy Reed-Solomon encodingwith a pillar number (T) of five and decode threshold number of three.In this example, a first data segment is divided into twelve data blocks(D1-D12). The coded matrix includes five rows of coded data blocks,where the first row of X11-X14 corresponds to a first encoded data slice(EDS 1_1), the second row of X21-X24 corresponds to a second encodeddata slice (EDS 2_1), the third row of X31-X34 corresponds to a thirdencoded data slice (EDS 3_1), the fourth row of X41-X44 corresponds to afourth encoded data slice (EDS 4_1), and the fifth row of X51-X54corresponds to a fifth encoded data slice (EDS 5_1). Note that thesecond number of the EDS designation corresponds to the data segmentnumber.

Returning to the discussion of FIG. 3, the computing device also createsa slice name (SN) for each encoded data slice (EDS) in the set ofencoded data slices. A typical format for a slice name 80 is shown inFIG. 6. As shown, the slice name (SN) 80 includes a pillar number of theencoded data slice (e.g., one of 1-T), a data segment number (e.g., oneof 1-Y), a vault identifier (ID), a data object identifier (ID), and mayfurther include revision level information of the encoded data slices.The slice name functions as, at least part of, a DSN address for theencoded data slice for storage and retrieval from the DSN memory 22.

As a result of encoding, the computing device 12 or 16 produces aplurality of sets of encoded data slices, which are provided with theirrespective slice names to the storage units for storage. As shown, thefirst set of encoded data slices includes EDS 1_1 through EDS 5_1 andthe first set of slice names includes SN 1_1 through SN 5_1 and the lastset of encoded data slices includes EDS 1_Y through EDS 5_Y and the lastset of slice names includes SN 1_Y through SN 5_Y.

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of a data object that was dispersed storage error encodedand stored in the example of FIG. 4. In this example, the computingdevice 12 or 16 retrieves from the storage units at least the decodethreshold number of encoded data slices per data segment. As a specificexample, the computing device retrieves a read threshold number ofencoded data slices.

To recover a data segment from a decode threshold number of encoded dataslices, the computing device uses a decoding function as shown in FIG.8. As shown, the decoding function is essentially an inverse of theencoding function of FIG. 4. The coded matrix includes a decodethreshold number of rows (e.g., three in this example) and the decodingmatrix in an inversion of the encoding matrix that includes thecorresponding rows of the coded matrix. For example, if the coded matrixincludes rows 1, 2, and 4, the encoding matrix is reduced to rows 1, 2,and 4, and then inverted to produce the decoding matrix.

FIG. 9A is a schematic block diagram of an embodiment of a storagemodule 84 that includes a writer 102, a reader 104, and queues 1-5. Thestorage module 84 can be implemented via a computing device 16 of FIG.1, the network 24 of FIG. 1. The computing device 16 can function as adispersed storage processing agent for computing device 14 as describedpreviously, and may hereafter be referred to as a distributed storageand task (DST) processing unit. Each dispersed storage (DS) unit 1-5 maybe implemented utilizing the storage unit 36 of FIG. 1. While the DSTprocessing unit is described below in conjunction with the operation ofcomputing unit 16, the operates may likewise be performed by other DSTprocessing units, including integrity processing unit 20 and/or managingunit 18 of FIG. 1.

The writer 102 generates messages for transmission to one or more DSunits of DS units 1-5. The reader 104 interprets messages received fromthe one or more DS units of DS units 1-5. The messages include requestmessages and response messages. Messages transmitted from the storagemodule 84 to DS units 1-5 include requests 1-5. Messages that thestorage module 84 receives from DS units 1-5 include responses 1-5.

Each queue of queues 1-5 may be implemented as one or more of a physicalmemory device, a plurality of memory devices, and a virtual allocationof storage capacity of one or more memory devices. Each queue may beassociated with a fixed storage capacity. Each queue of queues 1-5temporarily stores messages received from a DS unit waiting to beprocessed by the reader 104 or messages from the writer 102 to betransmitted to a DS unit. For example, the writer 102 stores message 3-5in queue 3 for transmission to DS unit 3. Message 3-5 are sent to DSunit 3 via a network when message 3-5 are to be transmitted inaccordance with a queue prioritization scheme.

The queue prioritization scheme may be based on one or more of a numberof messages associated with the queue (e.g., pending messages), aprioritization approach (e.g., first in first out (FIFO), last in lastout (LIFO)), a prioritization level associated with each of the messagesassociated with the queue, a network performance level, a DS unitperformance level, and an order of message receipt by the queue. Forinstance, queue 3 outputs message 3-5 to DS unit 3 when messages 3-1through 3-4 have been successfully sent in accordance with a FIFOprioritization approach of the queue prioritization scheme. As anotherinstance, queue 3 outputs message 3-5 to DS unit 3 when message 3-1 hasbeen successfully sent and prior to sending of messages 3-2 through 3-4when a prioritization level associated with message 3-5 is greater thana privatization level associated with messages 3-2 through 3-4 and theprioritization level associated with message 3-5 is lower than aprivatization level associated with message 3-1. As another example,queue 4 receives message 4-0 from DS unit 4 to be read by the reader104. Queue 4 outputs message 4-0 to the reader 104 in accordance withthe queue prioritization scheme.

The storage module 84 may delete a message stored in a queue when themessage is outputted and is no longer required. The storage module 84may change a message priority level of the message after message hasbeen stored in a queue to affect a modified message transmission order.The storage module 84 may delete the message stored in the queue whenthe message is no longer required. The method to determine whether themessage is no longer required, to delete the message, and to change themessage priority is discussed in greater detail with reference to FIGS.6B-10.

FIG. 9B is a schematic block diagram of another embodiment of acomputing system that includes a computing device 110 and a dispersedstorage network (DSN) memory 22 of a dispersed storage network. The DSNmemory 22 includes a plurality of storage nodes 112-116. The computingdevice 110 includes a dispersed storage (DS) processing 118. Thecomputing device 110 may be implemented as at least one of a userdevice, a DS processing unit, and a DS unit. The DS processing 118includes a generate messages module 120, a processing information module122, a prioritization module 124, and a messaging module 126. The systemfunctions to access the DSN memory 22 with regards to a set of encodeddata slices. The accessing includes at least one of reading the set ofencoded data slices from the DSN memory 22 and writing the set ofencoded data slices to the DSN memory 22. A data segment 128 of data isencoded using a dispersed storage error coding function to produce theset of encoded data slices. The generate messages module 120 receivesthe data segment 128 when the accessing includes writing the set ofencoded data slices to the DSN memory 22. For example, the generatemessages module 120 receives the data segment 128 and encodes the datasegment 128 to produce the set of encoded data slices when the accessingincludes writing the set of encoded data slices to the DSN memory 22. Asanother example, the DS processing 118 generates the data segment 128and encodes the data segment 128 to produce the set of encoded dataslices when the accessing includes writing the set of encoded dataslices to the DSN memory 22. Alternatively, the generate messages module120 receives the set of encoded data slices.

The generate messages module 120 generates a set of messages 130regarding the set of encoded data slices. The set of messages 130includes a set of read messages to read the set of encoded data slicesfrom the DSN memory 22 when the accessing includes reading the set ofencoded data slices from the DSN memory 22. A read message of the set ofread messages includes a read slice request. For example, the generatemessages module 120 generates a set of read slice requests that includesa set of slice names corresponding to the set of encoded data slices.The set of messages 130 includes a set of write messages to write theset of encoded data slices to the DSN memory 22 when the accessingincludes writing the set of encoded data slices to the DSN memory 22. Awrite message of the set of write messages includes a write slicerequest. For example, the generate messages module 120 generates a setof write slice requests that includes the set of encoded data slices andthe set of slice names corresponding to the set of encoded data slices.

The processing information module 122 determines system-level messageprocessing information 132 based on status of processing a plurality ofsets of messages regarding a plurality of sets of encoded data slices.The plurality of sets of messages regarding the plurality of sets ofencoded data slices may include numerous other write and read accessesof other encoded data slices within at least one storage node of theplurality of storage nodes 112-116. The processing information module122 determines the system-level message processing information 132 by aseries of steps. A first step includes, for a first set of messages ofthe plurality of sets of messages, determining at least one of: acurrent status of sending the first set of messages (e.g., the first setof messages have been sent to the DSN memory 22), and a current statusof successfully processing the first set of messages. The determiningincludes at least one of initiating a query, performing a lookup,executing a test, accessing historical records, and accessing themessaging module 126. The processing of the first set of messagesincludes at least one of retrieving and writing the set of encoded dataslices. For example, a current status of sending the first set ofmessages indicates that 5 messages of a set of 16 messages have beensent. Successfully processing the first set of messages may include atleast one of retrieving at least a decode threshold number of encodeddata slices of the set of encoded data slices and writing at least awrite threshold number of encoded data slices of the set of encoded dataslices. For example, a current status of successfully processing thefirst set of messages indicates successful processing when 11 encodeddata slices have been retrieved when a decode threshold number is 10. Asanother example, a current status of successfully processing the firstset of messages indicates unsuccessful processing when 12 encoded dataslices have been sent when a write threshold number is 13.

A second step of determining the system-level message processinginformation includes, for a second set of messages of the plurality ofsets of messages, determining at least one of: a current status ofsending the second set of messages, and a current status of successfullyprocessing the second set of messages. Alternatively, or in addition to,more steps may be included in the series of steps including determiningstatus with regards to further sets of messages of the plurality of setsof messages. A third step includes, determining the status of processingthe plurality of sets of messages regarding the plurality of sets ofencoded data slices based on the at least one of the current status ofsending the first set of messages and the current status of successfullyprocessing of the first set of messages, and the at least one of thecurrent status of sending the second set of messages, and the currentstatus of successfully processing of the second set of messages. Thedetermining includes at least one of aggregating status, selectingstatus, and confirming status. For example, the processing informationmodule 122 determines the status of processing the plurality sets ofmessages regarding the plurality of sets of encoded data slices byaggregating current status associated with 10 sets of messages when theplurality of sets of messages includes 10 sets of messages.

For a first message 136 of the set of messages 130, the prioritizationmodule 124 determines a first message priority 134 based on thesystem-level message processing information 132 and message processingstatus of a first storage node 112 of the plurality of storage nodes112-116. The prioritization module 124 determines the message processingstatus of the first storage node 112 by a series of steps. A first stepincludes determining a number of sets of the plurality of sets ofmessages that involves the first storage node (e.g., messages to be sentto the first storage node 112). A second step includes determiningstatus of sending messages of the number of sets of the plurality ofsets of messages to the first storage node 112. A third step includesdetermining status of successfully processed messages of the number ofsets of the plurality of sets of messages by the first storage node 112.A fourth step includes determining the message processing status of thefirst storage node 112 based on the status of sending messages and thestatus of successfully processed messages.

The prioritization module 124 determines the first message priority 134by a series of steps. A first step includes determining the number ofsets of the plurality of sets of messages that involves the firststorage node 112. A second step includes interpreting the system-levelmessage processing information 132 regarding the number of sets thatinvolve the first storage node 112 to produce interpreted system-levelmessage processing information. A third step includes interpreting themessage processing status of the first storage node 112 regarding thenumber of sets that involve the first storage node 112 to produceinterpreted message processing status. A fourth step includes applying aload balancing function in accordance the interpreted system-levelmessage processing information and the interpreted message processingstatus to produce the first message priority 134. The load balancingfunction includes at least one of a first in first out function, a lastin first out function, a time-based function, and a threshold-basedfunction. For example, the prioritization module 124 produces the firstmessage priority 134 to include a lower than average priority level whenthe interpreted system-level message processing information indicatesthat a plurality of other messages are pending to be sent to the firststorage node 112 where the plurality of other messages are associatedwith sets of encoded data slices that have not achieved processing of athreshold number of each set of the sets of encoded data slices. Themessaging module 126 sends the first message 136 of the set of messages130 to the first storage node 112 in accordance with the first messagepriority 134. For example, the messaging module 126 sends the firstmessage 136 to the first storage node 112 subsequent to sending anothermessage to the first storage node 112 when a message priority of theother message has greater priority than priority of the first messagepriority 134.

For a second message 140 of the set of messages 130, the prioritizationmodule 124 determines a second message priority 138 based on thesystem-level message processing information 132 and message processingstatus of a second storage node 114 of the plurality of storage nodes112-116. The messaging module 126 sends the second message 140 of theset of messages 130 to the second storage node 114 in accordance withthe second message priority 138. For example, the messaging module 126sends the second message 140 to the second storage node 114 prior tosending a different message to the second storage node 114 when amessage priority of the different message has less priority thanpriority of the second message priority 138.

The system further functions to update message priorities. Theprioritization module 124 updates the first message priority 134 basedon status of processing the set of messages 130. The prioritizationmodule 124 updates the second message priority 138 based on status ofprocessing the set of messages 130. The updating of message priorityincludes updating message priority associated with writing the set ofencoded data slices to the DSN memory 22 and reading the set of encodeddata slices from the DSN memory 22. The status of processing the sets ofmessages 130 includes status with regards to at least one of a number ofmessages of the set of messages that have been sent and/or processed anda number of messages of the set of messages that have been sent and/orprocessed within a given time period.

When the set of messages 130 includes the set of write messages to writethe set of encoded data slices to the DSN memory 22, the messagingmodule 126 determines when a write threshold number of the set of writemessages have been sent to the DSN memory 22. When the write thresholdnumber of the set of write messages have been sent and the first message136 has not yet been sent to the first storage node 112, theprioritization module 124 reduces the first message priority 134.Alternatively, the messaging module 126 determines when a writethreshold number of the set of write messages have been successfullyprocessed by the DSN memory 22. When the write threshold number of theset of write messages have been successfully processed and the firstmessage 136 has not yet been sent to the first storage node 112, theprioritization module 124 reduces the first message priority 134.

When the set of messages 130 includes the set of read messages to readthe set of encoded data slices from the DSN memory 22, the messagingmodule 126 determines when a decode threshold number of the set of readmessages have been sent to the DSN memory 22. When the decode thresholdnumber of the set of read messages have been sent and the first message136 has not yet been sent to the first storage node 112, theprioritization module 124 reduces the first message priority 134.Alternatively, the messaging module 126 determines when a decodethreshold number of the set of read messages have been successfullyprocessed by the DSN memory 22. When the decode threshold number of theset of read messages have been successfully processed and the firstmessage 136 has not yet been sent to the first storage node 112, theprioritization module 124 reduces the first message priority 134.

When the set of messages 130 includes the set of write messages to writethe set of encoded data slices to the DSN memory 22, the messagingmodule 126 determines that a write threshold number of the set of writemessages have not been sent to DSN memory 22 within a given time frame.When the write threshold number of the set of write messages have notbeen sent in the given time period and the first message 136 has not yetbeen sent to the first storage node 112 within the given time period,the prioritization module 124 increases the first message priority 134.

Alternatively, when the set of messages 130 includes the set of writemessages to write the set of encoded data slices to the DSN memory 22,the messaging module 126 determines when a write threshold number of theset of write messages have not been successfully processed by the DSNmemory 22 within a given time period. When the write threshold number ofthe set of write messages have not been successfully processed withinthe given time period and the first message 136 has not yet been sent tothe first storage node 112, the prioritization module 124 increases thefirst message priority 134.

When the set of messages includes a set of read messages to read the setof encoded data slices from the DSN memory 22, the messaging module 126determines when a decode threshold number of the set of read messageshave not been sent to the DSN memory 22 within a given time period. Whenthe decode threshold number of the set of read messages have not beensent within the given time period and the first message 136 has not yetbeen sent to the first storage node 112 in the given time period, theprioritization module 124 increases the first message priority 134.

Alternatively, when the set of messages 130 includes the set of readmessages to read the set of encoded data slices from the DSN memory 22,the messaging module 126 determines when a decode threshold number ofthe set of read messages have not been successfully processed by the DSNmemory 22 within a given time period. When the decode threshold numberof the set of read messages have not been successfully processed withinthe given time period and the first message 136 has not yet been sent tothe first storage node 112, the prioritization module 124 increases thefirst message priority 134.

FIG. 10 is a flowchart illustrating another example of modifying a writesequence. In particular, a method is presented for use with one or morefunctions and features described in conjunction with FIGS. 1-8 and 9Aand 9B. In step 180, a processing module (e.g., of a dispersed storage(DS) processing module) accesses write sequence information. The writesequence information includes one or more of a queue depth, a prioritylevel of a pending request, age of a pending request, number offavorable write responses received so far, and a write threshold number.The accessing may be based on one or more of retrieving a message queue,lookup, receiving a request, a query, and an error message.

The method continues at step 182 where the processing module determineswhether to elevate a priority level of a write sequence. The prioritylevel of the write sequence may be utilized in determining atransmission order of two or more pending write request messages of acommon queue such that a write request associated with a higher prioritylevel is transmitted prior to a write request associated with a lowerpriority level. The determining may be based on of the access writesequence information. For example, the processing module determines toelevate the priority level of the write sequence when the write sequenceis associated with an oldest write sequence of a plurality of writesequences that has not received a write threshold number of favorablewrite responses. Each write sequence of the plurality of write sequencesmay be associated with a different write threshold number. As anotherexample, the processing module determines to elevate the priority levelof the write sequence when the write sequence is associated with ahighest priority write sequence of the plurality of write sequences thathas not received the write threshold number of favorable writeresponses.

The method branches to step 186 when the processing module determinesnot to elevate the priority level of the write sequence. The methodcontinues to step 184 when the processing module determines to elevatethe priority level of the write sequence. The method continues at step184 where the processing module elevates the priority level of the writesequence. The elevating of the priority level includes at least one ofmodifying a priority level indicator of an associated write request in amessage queue to include a higher priority level number and reorderingpending write requests in the queue such that highest priority requestswill be transmitted next. The method continues to step 186.

The method continues at step 186 where the processing module determineswhether to lower the priority level of the write sequence. Thedetermining may be based on write sequence information. For example, theprocessing module determines to lower the priority level of the writesequence when the write sequence is associated with a write sequence ofa plurality of write sequences that has received a write thresholdnumber of favorable write responses. As another example, the processingmodule determines to lower the priority level of the write sequence whenthe write sequence is associated with a highest priority write sequenceof the plurality of write sequences that has received the writethreshold number of favorable write responses.

The method branches to step 190 when the processing module determinesnot to lower the priority level of the write sequence. The methodcontinues to step 188 when the processing module determines to lower thepriority level of the write sequence. The method continues at step 188where the processing module lowers the priority level of the writesequence. The lowering of the priority level includes at least one ofmodifying a priority level indicator of an associated write request in amessage queue to include a lower priority level number and reorderingpending write requests in the queue such that highest priority requestswill be transmitted next. The method continues to step 190. The methodcontinues at step 190 where the method can be repeated as required.

In various embodiments, a non-transitory computer readable storagemedium includes at least one memory section that stores operationalinstructions that, when executed by a processing system of a dispersedstorage network (DSN) that includes a processor and a memory, causes theprocessing system to access write sequence information corresponding toa write sequence; determine whether to elevate a priority level of thewrite sequence; when the processing system determines to elevate thepriority level of the write sequence, elevate the priority level of thewrite sequence; determine whether to lower the priority level of thewrite sequence; and when the processing system determines to lower thepriority level of the write sequence, lower the priority level of thewrite sequence.

It is noted that terminologies as may be used herein such as bit stream,stream, signal sequence, etc. (or their equivalents) have been usedinterchangeably to describe digital information whose contentcorresponds to any of a number of desired types (e.g., data, video,speech, audio, etc. any of which may generally be referred to as‘data’).

As may be used herein, the terms “substantially” and “approximately”provides an industry-accepted tolerance for its corresponding termand/or relativity between items. Such an industry-accepted toleranceranges from less than one percent to fifty percent and corresponds to,but is not limited to, component values, integrated circuit processvariations, temperature variations, rise and fall times, and/or thermalnoise. Such relativity between items ranges from a difference of a fewpercent to magnitude differences. As may also be used herein, theterm(s) “configured to”, “operably coupled to”, “coupled to”, and/or“coupling” includes direct coupling between items and/or indirectcoupling between items via an intervening item (e.g., an item includes,but is not limited to, a component, an element, a circuit, and/or amodule) where, for an example of indirect coupling, the intervening itemdoes not modify the information of a signal but may adjust its currentlevel, voltage level, and/or power level. As may further be used herein,inferred coupling (i.e., where one element is coupled to another elementby inference) includes direct and indirect coupling between two items inthe same manner as “coupled to”. As may even further be used herein, theterm “configured to”, “operable to”, “coupled to”, or “operably coupledto” indicates that an item includes one or more of power connections,input(s), output(s), etc., to perform, when activated, one or more itscorresponding functions and may further include inferred coupling to oneor more other items. As may still further be used herein, the term“associated with”, includes direct and/or indirect coupling of separateitems and/or one item being embedded within another item.

As may be used herein, the term “compares favorably”, indicates that acomparison between two or more items, signals, etc., provides a desiredrelationship. For example, when the desired relationship is that signal1 has a greater magnitude than signal 2, a favorable comparison may beachieved when the magnitude of signal 1 is greater than that of signal 2or when the magnitude of signal 2 is less than that of signal 1. As maybe used herein, the term “compares unfavorably”, indicates that acomparison between two or more items, signals, etc., fails to providethe desired relationship.

As may also be used herein, the terms “processing module”, “processingcircuit”, “processor”, and/or “processing unit” may be a singleprocessing device or a plurality of processing devices. Such aprocessing device may be a microprocessor, micro-controller, digitalsignal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on hard coding of thecircuitry and/or operational instructions. The processing module,module, processing circuit, and/or processing unit may be, or furtherinclude, memory and/or an integrated memory element, which may be asingle memory device, a plurality of memory devices, and/or embeddedcircuitry of another processing module, module, processing circuit,and/or processing unit. Such a memory device may be a read-only memory,random access memory, volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, cache memory, and/or any devicethat stores digital information. Note that if the processing module,module, processing circuit, and/or processing unit includes more thanone processing device, the processing devices may be centrally located(e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that if the processing module, module, processing circuit,and/or processing unit implements one or more of its functions via astate machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory and/or memory element storing the correspondingoperational instructions may be embedded within, or external to, thecircuitry comprising the state machine, analog circuitry, digitalcircuitry, and/or logic circuitry. Still further note that, the memoryelement may store, and the processing module, module, processingcircuit, and/or processing unit executes, hard coded and/or operationalinstructions corresponding to at least some of the steps and/orfunctions illustrated in one or more of the Figures. Such a memorydevice or memory element can be included in an article of manufacture.

One or more embodiments have been described above with the aid of methodsteps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claims. Further, the boundariesof these functional building blocks have been arbitrarily defined forconvenience of description. Alternate boundaries could be defined aslong as the certain significant functions are appropriately performed.Similarly, flow diagram blocks may also have been arbitrarily definedherein to illustrate certain significant functionality.

To the extent used, the flow diagram block boundaries and sequence couldhave been defined otherwise and still perform the certain significantfunctionality. Such alternate definitions of both functional buildingblocks and flow diagram blocks and sequences are thus within the scopeand spirit of the claims. One of average skill in the art will alsorecognize that the functional building blocks, and other illustrativeblocks, modules and components herein, can be implemented as illustratedor by discrete components, application specific integrated circuits,processors executing appropriate software and the like or anycombination thereof.

In addition, a flow diagram may include a “start” and/or “continue”indication. The “start” and “continue” indications reflect that thesteps presented can optionally be incorporated in or otherwise used inconjunction with other routines. In this context, “start” indicates thebeginning of the first step presented and may be preceded by otheractivities not specifically shown. Further, the “continue” indicationreflects that the steps presented may be performed multiple times and/ormay be succeeded by other activities not specifically shown. Further,while a flow diagram indicates a particular ordering of steps, otherorderings are likewise possible provided that the principles ofcausality are maintained.

The one or more embodiments are used herein to illustrate one or moreaspects, one or more features, one or more concepts, and/or one or moreexamples. A physical embodiment of an apparatus, an article ofmanufacture, a machine, and/or of a process may include one or more ofthe aspects, features, concepts, examples, etc. described with referenceto one or more of the embodiments discussed herein. Further, from figureto figure, the embodiments may incorporate the same or similarly namedfunctions, steps, modules, etc. that may use the same or differentreference numbers and, as such, the functions, steps, modules, etc. maybe the same or similar functions, steps, modules, etc. or differentones.

Unless specifically stated to the contra, signals to, from, and/orbetween elements in a figure of any of the figures presented herein maybe analog or digital, continuous time or discrete time, and single-endedor differential. For instance, if a signal path is shown as asingle-ended path, it also represents a differential signal path.Similarly, if a signal path is shown as a differential path, it alsorepresents a single-ended signal path. While one or more particulararchitectures are described herein, other architectures can likewise beimplemented that use one or more data buses not expressly shown, directconnectivity between elements, and/or indirect coupling between otherelements as recognized by one of average skill in the art.

The term “module” is used in the description of one or more of theembodiments. A module implements one or more functions via a device suchas a processor or other processing device or other hardware that mayinclude or operate in association with a memory that stores operationalinstructions. A module may operate independently and/or in conjunctionwith software and/or firmware. As also used herein, a module may containone or more sub-modules, each of which may be one or more modules.

As may further be used herein, a computer readable memory includes oneor more memory elements. A memory element may be a separate memorydevice, multiple memory devices, or a set of memory locations within amemory device. Such a memory device may be a read-only memory, randomaccess memory, volatile memory, non-volatile memory, static memory,dynamic memory, flash memory, cache memory, and/or any device thatstores digital information. The memory device may be in a form a solidstate memory, a hard drive memory, cloud memory, thumb drive, servermemory, computing device memory, and/or other physical medium forstoring digital information.

While particular combinations of various functions and features of theone or more embodiments have been expressly described herein, othercombinations of these features and functions are likewise possible. Thepresent disclosure is not limited by the particular examples disclosedherein and expressly incorporates these other combinations.

What is claimed is:
 1. A method for execution by a dispersed storage andtask (DST) processing unit that includes a processor, the methodcomprises: accessing, via the processor, write sequence informationcorresponding to a write sequence; determining, via the processor,whether to elevate a priority level of the write sequence based ondetermining when the write sequence is associated with an oldest writesequence of a plurality of other write sequences that has not received awrite threshold number of favorable write responses; when the processordetermines to elevate the priority level of the write sequence, theprocessor elevates the priority level of the write sequence;determining, via the processor, whether to lower the priority level ofthe write sequence; and when the processor determines to lower thepriority level of the write sequence, the processor lowers the prioritylevel of the write sequence.
 2. The method of claim 1 wherein the writesequence information includes one or more of: a queue depth, a prioritylevel of a pending request, an age of a pending request, a number offavorable write responses received, and the write threshold number. 3.The method of claim 1 wherein the accessing is based on one or more of:retrieving a message queue, a lookup, receiving a request, a query, andan error message.
 4. The method of claim 1 wherein the priority level ofthe write sequence is utilized in determining a transmission order oftwo or more pending write request messages of a common queue, wherein awrite request associated with a higher priority level is transmittedprior to a write request associated with a lower priority level.
 5. Themethod of claim 1 wherein determining to elevate the priority level ofthe write sequence is based on the write sequence information.
 6. Themethod of claim 1 wherein at least one of the plurality of other writesequences is associated with a different write threshold number.
 7. Themethod of claim 1 wherein determining to elevate the priority level ofthe write sequence is further based on determining when the writesequence is associated with a highest priority write sequence of theplurality of other write sequences that has not received the writethreshold number of favorable write responses.
 8. The method of claim 1wherein elevating of the priority level includes at least one of:modifying a priority level indicator of an associated write request in aqueue to include a higher priority level number, and reordering pendingwrite requests in the queue such that highest priority requests will betransmitted after the associated write request.
 9. The method of claim 1wherein determining to lower the priority level of the write sequence isbased on the write sequence information.
 10. The method of claim 1wherein determining to elevate the priority level of the write sequenceis further based on determining when the write sequence is associatedwith another write sequence of the plurality of other write sequencesthat has received the write threshold number of favorable writeresponses.
 11. The method of claim 1 wherein determining to elevate thepriority level of the write sequence is further based on determiningwhen the write sequence is associated with a highest priority writesequence of the plurality of other write sequences that has received thewrite threshold number of favorable write responses.
 12. The method ofclaim 1 wherein lowering of the priority level includes at least one of:modifying a priority level indicator of an associated write request in aqueue to include a lower priority level number, or reordering pendingwrite requests in the queue such that highest priority requests will betransmitted before the associated write request.
 13. A processing systemof a dispersed storage network comprises: at least one processor; amemory that stores operational instructions, that when executed by theat least one processor cause the processing system to: access writesequence information corresponding to a write sequence; determinewhether to elevate a priority level of the write sequence based ondetermining when the write sequence is associated with an oldest writesequence of a plurality of other write sequences that has not received awrite threshold number of favorable write responses; when the processingsystem determines to elevate the priority level of the write sequence,elevate the priority level of the write sequence; determine whether tolower the priority level of the write sequence; and when the processingsystem determines to lower the priority level of the write sequence,lower the priority level of the write sequence.
 14. The processingsystem of claim 13 wherein the write sequence information includes oneor more of: a queue depth, a priority level of a pending request, an ageof a pending request, a number of favorable write responses received,and the write threshold number.
 15. The processing system of claim 13wherein the priority level of the write sequence is utilized indetermining a transmission order of two or more pending write requestmessages of a common queue, wherein a write request associated with ahigher priority level is transmitted prior to a write request associatedwith a lower priority level.
 16. The processing system of claim 13wherein determining to elevate the priority level of the write sequenceis further based on determining when the write sequence is associatedwith a highest priority write sequence of the plurality of other writesequences that has not received the write threshold number of favorablewrite responses.
 17. The processing system of claim 13 whereindetermining to elevate the priority level of the write sequence isfurther based on determining when the write sequence is associated witha highest priority write sequence of the plurality of other writesequences that has received the write threshold number of favorablewrite responses.
 18. The processing system of claim 13 wherein theaccessing is based on one or more of: retrieving a message queue, alookup, receiving a request, a query, and an error message.
 19. Anon-transitory computer readable storage medium comprises: at least onememory section that stores operational instructions that, when executedby a processing system of a dispersed storage network (DSN) thatincludes a processor and a memory, causes the processing system to:access write sequence information corresponding to a write sequence;determine whether to elevate a priority level of the write sequencebased on determining when the write sequence is associated with anoldest write sequence of a plurality of other write sequences that hasnot received a write threshold number of favorable write responses; whenthe processing system determines to elevate the priority level of thewrite sequence, elevate the priority level of the write sequence;determine whether to lower the priority level of the write sequence; andwhen the processing system determines to lower the priority level of thewrite sequence, lower the priority level of the write sequence.